The document describes the different layers that make up the Earth. It begins with the crust, which is the outermost solid rocky layer varying in thickness from 35-70 km in continents to 5-10 km thick under oceans. Below the crust is the mantle, which is semi-molten rock around 2900 km thick and separated into upper and lower sections. The outer core is liquid and 2300 km thick, while the inner core is solid iron and nickel ball around 6000 miles below the surface.